Here we have the periodic table showing only the valence, or outer electrons in each element. It is these outermost electrons that determine an element’s reactivity. Some patterns should stand out.

2019 is the International Year of the Periodic Table. The person who typically gets credit for its creation is Dimitri Mendeleev. But there were many more chemists who should be recognized.

Periodic table Mendeleev’s periodic law has undergone certain changes and been complemented by new elements, including artificially synthesized ones.

150 years ago, Russian chemist Dmitrii Mendeleev created the periodic table of the elements, revolutionizing chemistry.

NEW YORK – They exist for only seconds at most in real life, but they’ve gained immortality in chemistry: Two new elements have been added to the periodic table. The elements were recognized ...